List of Primary State Highways in Washington

Primary State Highways were major state highways in the U.S. state of Washington used in the early 20th century. They were created as the first organized road numbering system in the state in stages between 1905 and 1937 and used until the 1964 state highway renumbering. These highways had named branch routes as well as secondary state highways with lettered suffixes. The system of primary and secondary state highways were replaced by sign routes (now state routes) to consolidate and create a more organized and systematic method of numbering the highways within the state.

History

The first state road, running across the Cascade Range roughly where State Route 20 now crosses it, was designated by the legislature in 1893 (However, this road wasn't actually opened until 1972). Two other roads—a Cascade crossing at present State Route 410 and a branch of the first road to Wenatchee—were added in 1897. The Washington Highway Department was established in 1905, and a set of twelve State Roads, numbered from 1 to 12, were assigned. A thirteenth was added in 1907, and State Roads 14 to 18 in 1909.

However, it was not until 1913 that a connected system was laid out—earlier state roads had been disconnected segments of road needing improvements. The seven primary roads were only assigned names, while the older state roads kept their numbers as secondary roads.